Virtual Photographer has some neat things, and a lot of not so neat things, but it's worth a look.

You can also Google for free PS actions, there's a lot of really interesting things out there that people have made. My favorite is the "Midnight" colors action and Gothic Glow, but there are so many. Just depends on what you're looking for really.

If you're drastically resizing images a lot - really big ones down for the web or normal size images into larger poster displays - then you'll really like Fred Miranda's Stair Interpolation action. Theoretically you could do it yourself, but it's slick with a nice GUI and only costs $20.